Drill grinding apparatus



May 18, 1937. H. E. TAUTZ DRILL GRINDING APPARATUS Filed Feb. 2, 1934 2 Sheets-Sheet 1 INVENTOR i 2/ 'q I ATTORNEY- May 18, 1937. TAUTZ I $080,515

' DRILL GRINDING APPARATUS Filed Feb. 2, 1954 2 Sheets-Sheet 2 "I -IQ. 5 I 310.6

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I .za' a g z! I 4 .3 8 ATTORNEY Patented May 18, 1937 UNITED STATES PATENT OFFICE DRILL GRINDING APPARATUS Herbert E. Tautz, Milwaukee, Wis.

Application February 2, 1934, Serial No. 709,437

9 Claims. (01. 51+-219) The invention relates to apparatus for grinding the points of twist drills, and more particularly to means for supporting and guiding the drills in relation to a grinding wheel.

It has heretofore been proposed to grind a twist drill by rocking it into engagement with a grinding wheel in such relation as to produce cutting clearance on the lips, but the mechanisms previously devised for this purpose have been of relatively complicated and expensive construction.

An object of the invention is to provide an improved but simplified drill grinding attachment which comprises a drill clamping holder having a detachable rockable mounting on supporting means for engaging'the drill with the grinding wheel, the holder being reversible on the supporting means to successively present the lips of the clamped drill to the grinding wheel, and the construction of the holder being such as to permit economical manufacture and convenient use.

Another object of the invention is to provide a drill grinding attachment in which the holder supporting means is movable toward and from the grinding wheel and is also adjustable parallel to the rocking axis of the holder.

The invention further consists in the several features hereinafter described and claimed.

In the accompanying drawings,

Fig. 1 is a top view of drill grinding apparatus embodying the invention;

Fig. 2 is a side view of the apparatus, parts being broken away;

Fig. 3 is a front view of the apparatus with the drill holder removed;

Fig. 4 is a view similar to Fig. 3 but showing a modified form of the invention;

Fig. 5 is a top view of the holder, parts being shown in longitudinal section, and parts being broken away;

Fig. 6 is a transverse sectional view of the holder taken along the line 6-6 of Fig. 5;

Fig. 7 is a detail view of parts of the holder;

Fig. 8 is a transverse sectional view of one of the holder jaws;

Fig. 9 is a top view of a modified form of holder;

Fig. 10 is a side view of drill grinding apparatus employing the holder of Fig. 9;

Fig. 11 is a detail view showing one step in grinding a fiat bottom drill, and

Fig. 12 is. a detail view showing another step in grinding a fiat bottom drill.

In that form of the invention shown in Figs.

1 to 3, 20 designates a. grinding wheel which is carried on a horizontal shaft 2| journalled in a frame 22 and driven in any suitable manner. A stud 23 is secured in the lower and forward portion of the frame 22 and extends parallel to the axis of the grinding wheel. A yoke 24 is pivotally carried on the stud 23 in axially slidable relation, and a coiled spring 25 interposed between the frame and yoke presses the yoke outwardly along the stud against an adjusting nut 26 at 10 the outer end of the stud.

The yoke is provided with spaced upwardly projecting arms 21 and 28, and is urged toward the grinding wheel by a coiled spring 29 connecting the arm 21 and frame 22, the position of the yoke with respect to the wheel being adjusted by a wing screw 30 threaded through the arm 21 and bearing against the frame 22.

The upper ends of the yoke arms 21 and 28 have aligned horizontal bores in which are slidably mounted conlcally pointed centers 3| and 32 clamped in adjusted position by screws 33 and 34, respectively, the latter preferably being a thumb screw. The center 32 is urged inwardly by a leaf spring 35 secured to the arm 28 and hearing against a shouldered portion of the center. A stop pin 36 on the center 32 limits the inward movement of the center. The center 32 may have a. knob 31 to facilitate its outward displacement.

The centers 3| and 32 are provided to rockably and detachably support thereon a drill holder or chuck 38, shown in detail in Figs. 5 to 8. The

cally opposite sides of which are integrally formed sector-shaped wings 40. The chuck body 35 and its wings may be conveniently formed by a die-casting or forging. The outer edges of the wings are provided with a number of conical recesses 4| to receive the centers 3| and 32. In the present instance, each wing has six recesses 4 l, as 40 seen in Fig. 2. When the holder is in horizontal position, as seen in Fig. 2, the recesses are arranged in vertically aligned pairs, one recess above and the other the same distance below the central horizontal plane of the holder. The mid- 45 die pairs of recesses in the wings are for use in grinding right-hand and left-hand fiat bottom drills, while the outer pairs are for use in grinding conically pointed right-hand and left-hand drills, as hereinafter described. In Figs. 1 and 2, 50 the device is being used with a right-hand conically pointed drill 42. The axes of all the upper recesses lie in the same horizontal plane and intersect at a common point, and the axes of all the lower recesses are similarly related in a lower 55 horizontal plane. The angles between the middle pairs of recesses and the outer pairs of recesses of each wing are equal and are substantially 31 in the case of ordinary drills. The axes of the middle pairs of recesses are at right-angles to the drill axis.

The conical body 39 has a conical chamber 48 therein opening at opposite ends. Drill-clamping jaws 44 in the form of triangular plates or vanes are arranged radially within the chamber 43, as seen in Figs. 5 and 6, and at their outer edges slidably engage the conical walls of the chamber, the inner drill-engaging edges of the jaws being parallel to the longitudinal axis of the chamber, and chamfered, if desired. to facilitate clamping of small diameter drills. The jaws 44, preferably of an even number not less than six, are guided in radial slots or channels formed between tapered spacers 4! fitting in the chamber 43 and secured to the walls thereof by screws 46, although in some instances, the fastening means may be omitted. The jaws 44 are urged into clamping engagement with the drill by a cap 41 threaded onto the large end of thechuck body and engaging the forward edges of the jaws, as seen in Fig. 5, the cap having an opening to admit the drill. The jaws are urged out of clamping engagement by coiled springs 49, one for each jaw, and each having a diameter greater than the thickness of the jaw and centrally fitting in a slot 50 formed in the jaw parallel to the outer edge of the jaw. The spring abuts at its inner end against shoulders formed by the bottoms of registering semi-cylindrical pockets 5| in the adja. cent spacers 45, as seen in Fig. 5, the pockets opening at the large ends of the spacers, as seen in Figs. 5 and "I. The longitudinal axis of each spring lies substantially in the median plane of the corresponding plate. In assembling the device, the spring'is placed in the slot 50 of the jaw and the jaw is then inserted between the spacers with the spring entering the pockets 5 l ing and held in the hands during the insertion and clamping of the drill. The drill projects a short distance from the small end of the chuck body for engagement with the grinding wheel, and this distance may be gaged by sighting notches 52, Fig. 2, formed in the tips of the wings 40. The drill is so placed that the cutting edges extend substantially parallel to an axial plane of the chuck passing centrally through the wings. The numerous clamping jaws insure centering of the drill even though their engagement islimited to the relatively narrow lands of the drill. When a smaller drill is clamped the clamping Jaws approach closer to the drill point so as to provide a rigid support for the drill.

After clamping the drill, the holder or chuck is ready to be mounted on its supporting centers, the center 32 being momentarily displaced against the action of its spring 35 to admit the chuckbetween the centers. The centers enter a pair of aligned recesses 4| in the chuck wings above the axis of the drill, after which the center I2 is clamped by the screw-34. The wing screw 30 is turned to advance the drill to the grinding wheel, and the nut 25 is turned to bring the drill point at the desired region of the face of the grinding wheel. The chuck is then tilted to move the drill point upwardly, thus grinding the cutting edge and the surface of the lip, the lip being ground with clearance by reason of the offset relation of the drill to the rocking axis. If the feed is too great, the chuck mounting will yield against the action of the spring 29. The nut 26 may be adjusted during the grinding operation to shift the position of the drill with respect to the face of the grinding wheel. When one lip is ground, the chuck is removed from its centers after loosening the screw 34, and replaced after turning it about the axis of the drill, the centers entering another pair of recesses in the chuck wings. The drill remains in clamped position during this changeover. The other lip of the drill is then ground in a similar manner, after which the chuck is removed from its centers and the drill removed from the chuck, ready for use. In the case of a left-hand drill, the chuck is mounted in the dotted line position shown in Fig. 1.

In the case of a flat-bottom drill 53. the procedure is illustrated in Figs. 11 and 12. The centers are received in the middle pairs of recesses of the chuck to grind the lips and provide clearance, a nub 54 being left at the center of the drill by grinding the drill near a side edge of the wheel 20. One aligned pair of the middle recesses 4| on the chuck are used when grinding one lip and the other pair for grinding the other lip. The nub 54 is then ground to form a conical cutting point 54', as indicated in Fig. 12.- The nut 26 isused to accurately adjust the position of the drill with respect to the flat side wall of the grinding wheel.

In the modified form of chuck mounting shown in Fig. 4, the centers 3| and 32 are carried on a forked bracket 24' which is slidably dovetailed on a base 22' for movement toward and from the grinding wheel 20, the bracket being adjusted by a hand screw 30'.

' In the modified form oi holder or chuck 38 shown in Figs. 9 and 10, the chuck body 39' has wings 40' provided with trunnions 4| arranged in aligned pairs, the axes of the aligned pairs being angularly related. With the chuck in horizontal position, the "axis of the active pair of trunnions is higher than the drill axis and the'axis of the other pair of trunnions is lower than the drill axis. The trunnions are removabiy and rockably supported in upwardly opening sockets 55 formed in arms of a pivoted forked yoke 50 similar to the yoke 24. The operation of the device of Figs. 9 and $0 is similar to that of the device of Figs. 1 and In all the embodiments of the invention, the

. drill remains clamped in the reversible holder or chuckduring the entire grinding operation so that both lips of the drill will be ground exactly the same, and this result is obtained by a simple structure having relatively few parts. The pivotal mounting of the holder is such as to compensate for wear, so as to preserve accuracy.

The device may also be used for grinding step drills, in which case the diameter of the cylindrical end portion of the drill may be reduced by engaging it with the side wall of the grinding wheel while rotating the drill in the holder, the holder jaws being slightly loosened for this purpose.

By providing the flat-bottom drill 53 with a conical cutting point, a flat-bottom bore may be drilled in a single operation instead of in two operations, first with a conicaliy pointed drill and then a pointless flat-bottom drill, as is the usual practice.

What I claim as new and desire to secure by Letters Patent is:

1. Drill grinding apparatus comprising a holder for clamping a drill and having a plurality of abutments at opposite sides for removable rocking engagement with supporting means, said abutments being arranged in selectively usable aligned pairs, the axis of one pair being angularly related to the axis of the other pair.

2. Drill grinding apparatus comprising a holder for clamping a drill and having a plurality of abutments at opposite sides for removable rocking engagement with supporting means, said abutments being arranged in selectively usable aligned pairs, the axis of one pair being on the opposite side of the drill axis from the axis of the other pair.

3. Drill grinding apparatus comprising a holder for clamping a drill and having a plurality of recesses at opposite sides for removable rocking engagement with pivotal supports, said recesses being arranged in selectively usablealigned pairs, the axis of one pair being on the opposite side of the drill axis from the axis of the other pair.

4. Drill grinding apparatus comprising a holder for clamping a drill and having a plurality of trunnions at'opposite sides for removable rocking engagement with supports, said trunnions being arranged in selectively usable aligned pairs, the axis of one pair being angularly related to the axis of the other pair.

5. Drill grinding apparatus comprising a hollow body having wings at opposite sides, there being abutments on said wings for removable rocking engagement with supporting means, said abutments being arranged in aligned pairs, and holding means for clamping a drill in said hollow body, the axis of one, pair of aligned abutments being on the opposite side of the drill axis from the axis of the other pair.

6. Drill grinding apparatus comprising a holder for clamping a drill and having a plurality of conical recesses at opposite sides for removable rocking engagement with conical centers,

said recesses being arranged in selectively usable aligned pairs, the axis of one pair being on the opposite side of the drill axis from the axis of the other pair. I

7. Drill grinding apparatus comprising a rockable holder for clamping a drill and having selectively usable positioning abutments at opposite sides for removable rockable engagement with supporting means, the axes of said selectively usable abutments being angularly related, said holder with its clamped drill being bodily removable from the supporting means and replaceable on said supporting means in reversed position for presenting opposite lips of the clamped drill to a grinding wheel.

8. Drill grinding apparatus comprising a drill holder, a grinding wheel for engaging the drill, a support for said holder having spaced aligned holder-engaging bearing members on which said holder is rockably and detachably mounted, and spring means for axially urging said members relatively toward each other into engagement with the holder, at least one of said bearing members being axially retractable against the action of said spring means for releasing said holder from said bearing members.

9. Drill grinding apparatus comprising a holder for clamping ,a drill and having a plurality of abutments at opposite sides for removable rocking engagement with supporting means, said abutments being arranged in selectively usable aligned pairs, the axis of one pair of abutments being angularly related to the axis of the other pair of abutments and being on the opposite side of the drill axis from the axis of the other pair of abutments.

HERBERT E. TAUTZ. 

